Protocol for window previews/thumbnails

Pekka Paalanen ppaalanen at
Wed Jun 1 08:00:44 UTC 2016

On Tue, 31 May 2016 14:49:38 +0100
adlo <adloconwy at> wrote:

> > On 20 May 2016, at 08:50, Pekka Paalanen <ppaalanen at> wrote:
> > 
> > You would design a new protocol extension private to Weston, with which
> > you deliver to your client the handles for top-level windows as they
> > come and go.
> >   
> This should probably be a separate protocol from the preview
> protocol. Is it possible to integrate the handle and preview protocol
> with another protocol, such as xdg-shell, so that the handles are
> delivered as xdg_surfaces and the preview protocol accepts
> xdg_surfaces as input?

No. Not for what you would like to use it. That simply is not what
xdg_surface is for, and none of the xdg_surface API or any other API
using xdg_surface would apply. So it is totally inappropriate to try to
shoehorn xdg_surface in there.

The handles would usually represent surfaces that have a xdg_surface
associated in the originating client, but it makes no sense to try to
call the handle a xdg_surface. The handles are used completely
differently than xdg_surfaces.

There is also a practical issue: to create an xdg_surface with
xdg_shell, you first need a wl_surface. However, you cannot refer to a
wl_surface of another client. That is the whole reason you need to
create handles in the first place, to be able to refer to surfaces that
are not your own.

> Is xdg-shell designed to be used by third-party clients for
> controlling windows in a similar way to libwnck? Does xdg-shell
> expose the inner workings of the compositor thus making it unsuitable?

As Jonas said, no.

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